Apparatus for making window envelopes

摘要

Disclosed are a method and an apparatus designed to make a window envelope rapidly using a water-soluble clarifying agent without causing an inconvenience in its window area. Upstream of an envelope making stage wherein a continuous paper while traveling along a continuous path of travel is successively folded, pasted and cut to form an envelope, a water-soluble clarifying agent is applied to an area on the continuous paper that is designed to become the transparent window in the envelope and the continuous paper carrying the clarifying agent is wound on a plurality of drying cylinders so that its surface carrying the clarifying agent faces outwards to dry the clarifying agent while holding the surface of paper carrying the clarifying agent out of contact with the drying cylinders.